1. Field of the Invention
The present invention relates in general to on-line sampling and analysis of a solid particulate suspended in a fluid, such as a phosphate rock, other minerals, grains, seed and other solids suspended in water, air, or other liquids or gases. More particularly, the invention relates to positioning a vortex tube in a process stream above a sample presentation area such as a light transparent window for removing deposited particulates, such as phosphates, and allowing for the collection of subsequent samples, in which the vortex tube provides a bypass to return the particulate samples to the flow downstream of the sample presentation area for continuous operation without interruption of the flow in the sampling line.
2. Description of the Related Art
Presently, phosphate rock is recovered from a sand-clay mixture that is mined from mineral deposits. Industrial recovery of solids of a few millimeters or less, such as phosphate rock, e.g., &lt;1 mm, begins with chemical treatment of a liquid aqueous slurry which includes a long chain hydrocarbon liquid. These hydrocarbons attach to the phosphate rock and are hydrophobic in nature. Thus, after they attach to the rock, the phosphate rock is forced out of the water phase to the surface in an aeration tank called a flotation cell. The flotation cell must be monitored to ensure maximum recovery of the phosphate rock. The phosphate content in the slurry exiting the flotation cell after the removal of the hydrocarbon-bound phosphate rock, also known as tailings, is a representative indicator of flotation cell performance.
Phosphate rock found in the tailings is considered unrecoverable and a lost natural resource. Normal operation of the flotation cell involves operator estimation of cell performance by visual inspection of the tailings. To optimize the operator's control of the flotation cell, it would be desirable therefore to provide a system and a method of continuously monitoring phosphate tailings to provide feedback to the operator to improve the performance and efficiency of the flotation cell operation. To this end, it is usually desirable to maintain the %BPL content in the tailings streams below 3% for acceptable cell performance.
U.S. Pat. No. 5,396,260 to Adel et al. for "Video Instrumentation for the Analysis of Mineral Content in Ores and Coal" issued Mar. 7, 1995, discloses the determination of mineral content using a video system in which digitized images having assigned gray levels are analyzed to determine the content of particular minerals in a coal slurry determined from the distribution of the gray levels. Slip streams are extracted from the tailings and feed lines which are allowed to pass through a thin sample chamber with flat glass plates on either side, the sample chamber being enclosed in a light type box with a video camera to provide a reflected light image for sample analysis. However, such slip streams extracted from the tailings and feed lines, are not in line with the tailings stream but merely tapped away from the fluid media being processed and may not be representative of the sampling of an on-line flowing slurry.
U.S. Pat. No. 4,797,550 to Nelson et al. for "Fiber Optic Detector for Flotation Cell Processing" issued Jan. 10, 1989 discloses a fiber optic detector submerged in a coal slurry to monitor a coal separation process. Light transmitted by an optical fiber is directed toward the slurry, and thus scattered by the slurry, from which a portion of the light is deflected back to the fiber optic detector, from which the light intensity reflected by the slurry is used to detect the mineral content in the slurry. Accordingly, only a small sample separated from the slurry is analyzed, which may not be representative of the on-line stream.
It would be desirable therefore to provide on-line sampling in which sampling of the particulate content in a fluid media is provided in-line with the process stream to collect representative particulate samples, such as phosphate rock and sand in a tailings line. An in-line sample presentation assembly would be advantageous for the collection of samples from the tailings where the sample could be returned to a slurry stream for continuous operation without interruption of the flow in the sampling line.